Method of forming flowmeter tube mandrels



, Sept. 18, 1945. c, E. cox 2,384,800

METHOD OF FORMING FLOWMETER TUBE MANDRELS Filed Jan. 22, 1942 2 Sheets-Sheet l 197' 7' OE/VE K7 BY fiw m Sept. 18, 1945. c, E, cox 2,384,800

METHOD OF FORMING FLOWMETER TUBE MANDRELS Filed Jan. 22, 1942 2 Sheets-Sheet 2 INVENTOR.

BY f/azzdz (5527 Patented Sept. 18, 1945 METHOD OF FORMIN MAND G FLOWMETER TUBE RELS Claude E. Cox, Detroit, Mich. Application January 22, 1942, Serial No. 427,759

4 Claims.

This invention relates to an improved'method of shaping a mandrel, which mandrel is adapted to be employed in the molding of a tapered fluted glass flowmeter tube.

The flowmeter tube which is formed upon the mandrel fabricated by the improved process herein described, constitutes part of a, complete flowmeter device which device is employed to make accurate determinations of liquid flow. The flowmeter tube which is formed upon the mandrel herein described exhibits a flow passage bore which tapers from one end to the other. This tapered bore is provided with a plurality of inwardly projecting linearly extending circumferentially spaced apart ribs disposed parallel to the axis of the bore. The flowmeter tube is formed of glass or other transparent material so that the position of a float mounted therein for travel as guided by said ribs may be readily determined and read against a scale which extends linearly along the tube.

Due to the accuracy of the determinations sought to be made with such device great accuracy in the shaping of the mandrel is required. My improved method is designed to achieve such accuracy. Through the use of my improved method a mandrel of the character required is formed without imposing any stresses thereon tending to produce inaccuracy of shape. The stock from which the mandrel is-shaped is supported without stress parallel its linear axis during the formation of the flutes and also during the tapering of the ribs which are intermediate the flutes.

Accuracy of formation of the mandrel is therefore a necessity and this invention includes an improved method of forming such a mandrel. Accuracy of the mandrel is not only necessary to insure accuracy of the tube formed thereon but is necessary to permit withdrawal of the formed tube from the mandrel. inaccuracy in contour of the mandrel or a slight reverse taper present thereon would prevent withdrawal of the tube therefrom. The accurate formation of the mandrel is therefore of prime importance. method of forming the mandrel herein set forth is such that the normal tension or stresses occurring in the shaping of the steel rod from which the mandrel is formed are prevented from pro-- ducing inaccuracies in the formed mandrel. Accuracy within substantially less than onethousandth of an inch is attained.

Other objects, advantages, and meritorious features of the invention will more fully appear Thefrom the following specification, appended claims, and accompanying drawings, wherein:

Figure 1 is a vertical sectional view through an upright fluid flow indicator tube as formed upon a mandrel made by my improved process,

Fig. 2 is an elevation of the mandrel upon which the tube of Fig. 1 is formed,

Figs. 3 'and 4 are views taken respectively on section lines 3-3 and 4-4 of Fig. 1,

Figs. 5 and 6 are views taken respectively on section lines 5-5 and 6-6 of Fig. 2,

Fig. 7 is a reduced view of a fluid flow indicator including the tube of Fig. 1 showing a measuring scale disposed alongside of the tube on which the position of the float indicator within the tube may be read,

Fig. 8 is a plan of the supporting bed plate of a milling machine fixture for holding the rod from which the mandrel is formed during the shaping of such rod, according to my improved process, Fig. 9 is a view taken on section line 9-9 of Hg. 8,

Figs. 10 and 11 are sectional views taken respectively on section lines ill-I0 and ll ll of Fig. 8, Fig. 11 being partly broken away.

The fluid flow indicator tube !8 illustrated in Figs. 1 and '7 which is formed on the mandrel fabricated according to my invention may be formed of glass or other suitable transparent material. It has a fluid passage bore 20 which is tapered from top to bottom. This bore consists of a plurality of flutes (four are here shown) separated by lands or ribs 22 which extend linearly 0f the tube and are equally spaced circumferentially about the bore as shown in Figs. 3 and 4.

The flutes establish the taper of the bore, note Fig. 3 as compared with Fig. 4, and the line indicating the bore in Fig. 1, which line is along the bottom of the flutes. This taper is accurately formed. The interior surfaces of the lands, however, are accurately formed parallel to the axis of the tube and spaced equidistant therefrom. The faces of the lands therefore constitute linear segments of a cylinder whose axis corresponds with the axis of the bore while the bottoms of the flutes form linear segments of a truncated cone straight side or curved as herein set forth whose axis corresponds with the axis of such cylinder end of the bore.

Mounted within the bore of the tube is an indicator float having a float body 26 which carries a disc 28 apertured as at 29 supported thereabove upon a relatively short stem 30. The float body 26 and disc 28 have diameters which form accurately close but freely sliding engagement with the land 22 of thebore 2!! of the tube so that the float will rise and fall freely within the tube dependent upon the rate of fluid flow up wardly through the tube.

The lands so guide the float within the tube that it will not wobble therein and the annular passageway established by the float within the tube bore relative to the bottoms of the flutes M w l remain a true annulus and will not temporarily assume a crescent shape as would be the case if the float wobbled in its rise and fall. Only through preserving a true annulus can accuracy of registration be attained. It will be noted that the tapered bore established by the bottoms of the flutes substantially merges with the lands at the lower end and the bore extends therebelow as a cylindrical bore within which cylindrical portion the float indicator rests when not in use.

This interiorly fluted tapered tube is mounted in a fluid flow line as indicated by conduits 32 and 32a. Fluid is passed through the line upwardly through the tube. The float indicator rises and falls in response to variation in rate of flow of the fluid passing through the tube. The position of the indicator float within the tube may be read upon the scale 33 in any desired rate of flowmeasurement with which the scale may be calibrated. Obviously if desired the scale might be etched on the outer surface of the glass tube. The above described flow meter tube does not constitute the invention herein claimed, but is of assistance in understanding the invention of the method of forming the mandrel which is claimed herein.

The fluted tapered tube is formed on the mandrel 34 shown in Fig. 2. Such mandrel may be formed from a steel rod as hereinafter described but it will be observed that it has a fluted tapered portion wh'erein flutes 38 are separated by ribs 38. The ribs 38 are tapered from top to bottom so that their outer surfaces form linear seg= merits, equally spaced circumferentially of the rod, of a truncated coneas hereinbefore specifled whose axis corresponds with the axis of the mandrel. The bottoms of the flutes 36 are equally circumferentially spaced about the mandrel and constitute linear segments of a cylinder whose axis corresponds with the axis of the mandrel or rod. In other words, the bottoms of the flutes are in parallelism with the axis of the rod throughout their length and are spaced equidistant radially from such axis. At the lower end of the mandrel the ribs substantially merge with the bottoms of the flutes and the mandrel extends therebelow in cylindrical form so that th tube formed on the mandrel also has a cylindrical portion We immediately adjacent and below its fluted portion as shown in Fig. l and as heretofore described.

In the formation of the fluted tapered tube upon the mandrel a cylindrical glas tube having a cylindrical bore of a size to be received over the mandrel is mounted upon the mandrel and heated to be constricted about the mandrel and molded to shape thereon. The method of molding the tube upon the mandrel forms no part of the invention herein claimed.

The formed mandrel is shown in Fig. 2 and cross-sectional views are shown in Figs. 5 and 6. Figs. 8 to 11 illustrate steps in the process of the manufacture of the mandrel. In the manufacture of themandrel a straight cylindrical rod of suitable length, indicated as 10, is clamped within a channel formed in a bed plate I2 of a milling machine fixture. This channel is indicated generally as H and has V-shaped entrance walls 18 upon which the rod is seated as shown at the right in Fig. 10. Thi channel and the V-walls I6 are truly formed and truly shaped clamps 18 are provided and held down by adjusting screws 80 to clamp the rod upon the V-faces IS in a position of parallelism with its axis.

A cutting element 82 is then employed to form flute 36 in the rod. Upon the formation of the one flute 36 the rod is rotated and a second flute is formed. The operation is repeated and the four flutes 36 shown in Figs. 5 and 6 are thus formed. These flutes have bottoms which are arcuate and constitute linear segments, equally circumierentially spaced about the rod, of a cylinder whose axis corresponds with the axis of the rod.

Following the formation of the four flutes 8b the fluted rod is then positioned within a second channel it as shown in Figs. 9 and 11, which channel also has V-shaped entrance side walls 16 as shown in Fig. 11 or as shown at the left in Fig. 10. Suitable clamps 18 are again employed to hold the rod accurately in parallelism upon the accurately formed sides of this channel. In this instance the rod is supported by the V- shaped sides at the entrance of the channel upon the bottoms of two adjacent flutes and one rib 3b is received within the lower portion 1d of the channel as shown in Figs. 10 and 11. The diametrically opposed rib 3B is positioned to be acted upon by a cutting tool 83 as shown in Fig. 9 to taper the fillet. Such rib is then tapered. The operation is repeated until after the four ribs have been similarly tapered and a mandrel such as shown in Fig. 2 results.

Due to the manner in which the rod is clamped upon the supporting bed plate and the fact that it is held securely in parallelism and the flutes are first formed, which flutes have bottoms that are in parallelism with the axis of the rod, it is possible to thereafter support the rod upon these bottoms of the flutes and to accurately taper the ribs 38 so that the complete mandrel exhibits an accurately tapered surface established by the fillets and an accurate cylindrical surface established by the bottoms of the flutes. The tapered surfaces established by the outer faces of the rilbs form a truncated cone whose axis corresponds with the axis of the cylinder established by the bottoms of the flutes and with the axis of the rod itself. In the structure shown the ribs merge at the small end of the mandrel into the cylindrical surface established by the bottoms of the flutes and the mandrel therebelow is cylindrical in form.

It is believed that the above described method of forming the mandrel is the most desirable one. It may be supported and cut away and such operations may be carried out accurately without the stresses or tensions which arise in the cutting of a steel rod of this length producing inaccuracy of result. It is apparent that tostrip a glass tube conforming closely with the contour of the mandrel from the mandrel it is necessary,

that there be no reverse taper or inaccuracy of contour present in the mandrel.

Whatlclaimis: p

i. That method of forming a mandrel comprising supporting a straight cylindrical rod throughout its length upon a surface of the rod extending parallel to its axis and cutting the rod to form a plurality of flutes therein extending linearly thereof and spaced apart circumferentially thereazbout by rib portions and so forming said flutes that they exhibit bottoms disposed in parallelism with the axis of the rod and spaced equidistant therefrom throughout their length, thereafter supporting the rod throughout its length upon the bottoms of certain of said flutes and tapering the ribs between the flutes from one end to the opposite end thereof.

2. That method of forming a mandrel comprising holding a straight cylindrical rod within a V groove support disposed in parallelism with the axis of the rod while removing material from the rod to form a flute extending linearly of the rod and having a bottom extending parallel to the axis, of the rod, repeating said holding and material removing operation to successively form a plurality of flutes each extending linearly of the rod and each having a bottom extending parallel to the axis of the rod, saidflutes being spaced apart circumferentially of the rod by ribs,

thereafter holding the fluted rod upon a support within a channel having a V-shaped entrance with the bottoms of two of the flutes seated against opposite sides of said entrance and with one rib between said two flutes disposed within saidchannel and tapering the opposite rib from one end to the other, repeating said holding and tapering operations successively similarly tapering the several ribs,

3. That method of forming a mandrel comprising supporting a straight cylindrical rod throughout its length upon circumferentially spaced surfaces of the rod extending parallel to its axis and cu ting the rod surface diametrically opposite the space between said supported surfaces, successively repeating said operations, to form a plurality oi flutes therein extending linearly thereof and spaced apart circurnierentlally thereabout by rib portions, and so forming said flutes that they exhibit bottoms disposed in parallelism and concentric with the axis of the rod and spaced equidistant therefrom throughout their length, thereafter supporting the rod throughout its length upon the bottoms of certain of said flutes and tapering the ribs'between the flutes from one end to the opposite end thereof.

4. That method of forming a mandrel comprising holding a straight cylindrical rod vwithin a the axis thereof, repeating said holding and ma-.

terial removing operation to successively form a plurality of flutes each extending linearly of the rod and each having a bottom concentric with and extending parallel to the rod axis, said flutes being spaced apart circumierentially of the rod by ribs, thereafter holding the fluted rod upon said support with the bottoms of two of the flutes seated against opposite side walls of said groove and with one rib between said flutes disposed therein and tapering the opposite rib from one end to the other, and repeating said holding and tapering operations successively to similarly taper the several ribs.

CLAUDE E. COX. 

